Plastic centrifuge bottles and caps therefor



Aug. 9, 1966 D. F. MITCHELL 3,265,296

PLASTIC CENTRIFUGE BOTTLES AND CAPS THEREFOR Filed March 1964 2 Sheets-Sheet 2 B lwezafoad:

United States Patent 3,265,296 PLASTIC CENTRIFUGE BOTTLES AND CAPS THEREFOR David F. Mitchell, Tewksbury, Mass., assignor to International Equipment Company, Needham, Mass., a corporation of Massachusetts Filed Mar. 6, 1964, Ser. No. 349,837 3 Claims. (Cl. 233-26) The present invention relates to plastic bottles for use in centrifuges and to their caps.

While plastic centrifuge bottles are widely used, they have the serious objectionable feature that, when filled and sealed, their walls, if unsupported, are incapable of resisting distortions during centrifugation. As a consequence, rupturing occurs as does failure of the caps to prevent leakage. In practice, such bottles are used in centrifuges of the type having a rotor provided with a plurality of downwardly and outwardly inclined cylindrical cavities for bottles or tubes, the cavities being spaced an equal distance from each other and from the axis of the rotor. The bottles protrude from the cavities so that the rotor cannot provide them with the support necessary to prevent bottle or cap failures.

It is, accordingly, essential to reinforce the upper end of each plastic centrifuge bottle and the present invention is concerned with means for so doing. In accordance with the invention, this general objective is attained with a plastic bottle of the type having an externally threaded neck. A cap is provided that includes a closure having a disc member dimensioned to overlie and be supported by the rnouth of the bottle the closure is provided with a circumferential groove for a seal which engages a seat in the bottle mouth. A jacket has -a neck portion internally threaded for attachment to the neck of the bottle and a skirt portion to overlie and reinforce the shoulder portion thereof. The neck portion of the jacket is exteriorly threaded to receive a retainer having a clamping portion engageable with the portion of the sealcarrying member in a zone holding it in the bottle mouth and bringing the seal into sealing engagement with the bottle mouth seat.

A particular objective of the invention is to provide a bottle the inner portion of Whose mouth is downwardly and inwardly inclined to provide the seat and closure in which the circumferential groove for the seal is at the junction of the disc member and a cylindrical portion dimensional for entry into the mouth of the bottle.

In the accompanying drawings, there is shown an illustrative embodiment of the invention from which these and other of the objectives, novel features, and advantages will be apparent.

In the drawings:

FIGURE 1 is a partly sectioned side elevation of a centrifuge rotor supporting a vertically sectioned, centrifuge bottle in accordance with the invention,

FIGURE 2 is a fragmentary view of the centrifuge rotor showing the cap end of the bottle, and

FIGURE 3 is an exploded view, on an increased scale, of the cap and of the neck end of the bottle, the parts being vertically sectioned.

A centrifuge rotor typically has a series of cylindrical cavities 11 inclined outwardly and downwardly from a central recess 12. Only one such cavity 11 is shown 3,265,296 Patented August 9, 1966 "ice but it will be appreciated that the several cavities 11 are equally spaced from each other and from the axis of the rotor 10. The upper end of each cavity 11 has a counterbored portion 11A.

A plastic centrifuge bottle is generally indicated at 13 and has an externally threaded neck 14 establishing a shoulder 15. The walls of the bottles 13 are flexible as they are molded from such plastic stock as polyethylene, polypropylene or polycarborates. As may best be seen in FIGURE 3, the mouth 16 of the bottle 13 has an inwardly and downwardly inclined inner portion 17 which constitutes a seat. The diameter of the bottle 13 is such that the bottle is a close but free fit in a cavity 11 and its height is such that its neck 14 protrudes from the upper end thereof as shown in FIGURE 1.

The bottle 13 is provided with a cap comprising a disc member generally indicated at 18 and having a disc member 19 dimensioned to overlie and be supported by the bottle mouth 16 and a depending cylindrical portion 20 dimensioned to fit freely therein. The member 18 has a circumferential groove 21 at the junction of its portions 19 and 20 for a seal 22, preferably a seal of the so-called O-ring type. The seal 22 protrudes from its groove 21 sufficiently to engage the seat 17 when the member 18 is placed on the mouth 16 with its cylindrical portion 20 entrant thereof.

The bottle cap also includes a reinforcing metal jacket, generally indicated at 23, and having a neck portion 24 that is both internally and externally threaded and a portion 25 overlying and extending below the bottle shoulder 15. The jacket 23 is threaded on the neck 14 of the bottle 13 until it seats against the shoulder 15 and is dimensioned to be a free but close fit within the counterbore 11A of the cavity 11.

With the jacket 23 and the member 18 both in place, the internally threaded sleeve 26 of the retainer 27 is threaded on the jacket 23 with the retainer 27 engaging the disc member 19 and placing the O-ring 22 under effective sealing pressure. It is preferred that the retainer 27 have a central opening 28 dimensioned to receive a boss 29 centrally of the disc member 19.

I claim:

1. In combination, a centrifuge rotor having a plurality of angularly disposed cavities, each cavity having a counter bore in its upper end, a plastic centrifuge bottle dimensional to fit a rotor cavity and including an externally threaded neck defining a shoulder, the open end of said neck constituting an annular, outwardly exposed seat; a jacket including a neck portion threaded on said bottle neck and a skirt portion overlying the shoulder of said bottle, and extending a short distance below said shoulder, said skirt portion dimensioned to fit a counter bore, the neck portion of said jacket being externally threaded; and a cap comprising a retainer threaded on said neck portion and including a clamping portion overlying the mouth of said bottle, a closure including a disc member overlying said mouth and fitting freely within said retainer under said clamping portion, and an annular seal of the O-ring type carried by said closure and seated on said seat, said jacket neck portion being positioned relative to said seat and the threaded connection between said jacket neck portion and said retainer being of sufiicient extent to enable said seal to be compressed axially between said seat and said disc member by said clamping portion as said retainer is secured.

2. The combination of claim 1 in which the upper end of the neck portion of the jacket terminates below the open end of the neck of the bottle.

3. The combination of claim 1 in which the open end of the neck has its inner edge inwardly and downwardly beveled to establish the seat and the closure includes a cylindrical portion freely fitting the bottle mouth and having an annular recess, and the annular seal is within the recess but protrudes therefrom to engage said seat when the closure is placed on the bottle mouth.

References Cited by the Examiner UNITED STATES PATENTS Keeran 215-40 Prindle 215-40 Brinton 215-12 Baltosser 21540 Piemonte et 211. 

1. IN COMBINATION, A CENTRIFUGE ROTOR HAVING A PLURALITY OF ANGULARLY DISPOSED CAVITIES, EACH CAVITY HAVING A COUNTER BORE IN ITS UPPER END, A PLASTIC CENTRIFUGE BOTTLE DIMENSIONAL TO FIT A ROTOR CAVITY AND INCLUDING AN EXTERNALLY THREADED NECK DEFINING A SHOULDER, THE OPEN END OF SAID NECK CONSTITUTING AN ANNULAR, OUTWARDLY EXPOSED SEAT;-A JACKET INCLUDING A NECK PORTION THREADED ON SAID BOTTLE NECK AND A SKIRT PORTION OVERLYING THE SHOULDER OF SAID BOTTLE, AND EXTENDING A SHORT DISTANCE BELOW SAID SHOULDER, SAID SKIRT PORTION DIMENSIONED TO FIT A COUNTER BORE, THE NECK PORTION OF SAID JACKET BEING EXTERNALLY THREADED; AND A CAP COMPRISING A RETAINER THREADED ON SAID NECK PORTION AND INCLUDING A CLAMPING PORTION OVERLYING THE MOUTH OF SAID BOTTLE, A CLOSURE INCLUDING A DISC MEMBER OVERLYING SAID MOUTH AND FITTING FREELY WITHIN SAID RETAINER UNDER SAID CLAMPING PORTION, AND AN ANNULAR SEAL OF THE O-RING TYPE CARRIED BY SAID CLOSURE AND SEATED ON SAID SEAT, SAID JACKET NECK PORTION BEING POSITIONED RELATIVE TO SAID SEAT AND THE THREADED CONNECTION BETWEEN SAID JACKET NECK PORTION AND SAID RETAINER BEING OF SUFFICIENT EXTENT TO ENABLE SAID SEAL TO BE COMPRESSED AXIALLY BETWEEN SAID SEAT AND SAID DISC MEMBER BY SAID CLAMPING PORTION AS SAID RETAINER IS SECURED. 